Distillation
Distillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction. Commercially, distillation has a number of applications. It is used to separate crude oil into more fractions for specific uses such as transport, power generation and heating. Water is distilled to remove impurities, such as salt from seawater. Air is distilled to separate its components—notably oxygen, nitrogen, and argon—for industrial use. Distillation of fermented solutions has been used since ancient times to produce distilled beverages with a higher alcohol content. The premises where distillation is carried out, especially distillation of alcohol, are known as a distillery. History ]] Early types of distillation were known to the Babylonians in Mesopotamia (in what is now Iraq) from at least the 2nd millennium BC.Martin Levey (1956). "Babylonian Chemistry: A Study of Arabic and Second Millennium B.C. Perfumery", Osiris 12, p. 376-389. Archaeological excavations in northwest Pakistan have yielded evidence that the distillation of alcohol was known in the Indian subcontinent since 500 BC, but only became common between 150 BC - 350 AD.Allchin 1979 Primitive tribes of India used a method of distillation for producing Mahuda liquor. This crude and ancient method is not very effective.Forbes 1970: 53-54 Distillation was later known to Hellenistic alchemists from the 1st century AD, and the later development of large-scale distillation apparatus occurred in response to demands for spirits. According to K. B. Hoffmann the earliest mention of "destillatio per descensum" occurs in the writings of Aetius, a Byzantine physician from Mesopotamia during the 5th-6th centuries.Distillation - LoveToKnow 1911 In Egypt, the female philosopher Hypatia of Alexandria is credited with having invented an early distillation apparatus, Biology, Joan Solomon, Pat O'Brien, Peter Horsfall, Nelson Thornes, p.41 and the first clear description of early apparatus for distillation is given by the Egyptian alchemist Zosimos of Panopolis in the fourth century. The invention of highly effective "pure distillation" is credited to Arabic and Persian chemists in the Middle East from the 8th century. They produced distillation processes to isolate and purify chemical substances for industrial purposes such as isolating natural esters (perfumes) and producing pure alcohol.Robert Briffault (1938), The Making of Humanity, p. 195: The first among them was Jabir ibn Hayyan (Geber), in the 8th century, who is credited with the invention of numerous chemical apparatus and processes that are still in use today. In particular, his alembic was the first still with retorts which could fully purify chemicals, a precursor to the pot still, and its design has served as inspiration for modern micro-scale distillation apparatus such as the Hickman stillhead.Microscale Laboratory Techniques - Distillation from McMaster University The isolation of ethanol (alcohol) as a pure compound through distillation was first achieved by the Arab chemist Al-Kindi (Alkindus). Petroleum was first distilled by the Persian alchemist Muhammad ibn Zakarīya Rāzi (Rhazes) in the 9th century, for producing kerosene, while steam distillation was invented by Avicenna in the early 11th century, for producing essential oils. As the works of Middle Eastern scribes made their way to India and became a part of Indian alchemy, several texts dedicated to distillation made their way to Indian libraries. Among these was a treatise written by a scholar from Bagdad in 1034 titled Ainu-s-Sana'ah wa' Auna-s-Sana'ah.Forbes 1970: 42 Scholar Al-Jawbari travelled to India.Forbes 1970: 45 By the time of the writing of the Ain-e-Akbari, the process of distillation was well known in India.Forbes 1970: 54 Distillation was introduced to medieval Europe through Latin translations of Arabic chemical treatises in the 12th century. In 1500, German alchemist Hieronymus Braunschweig published Liber de arte destillandi (The Book of the Art of Distillation)Magnum Opus Hermetic Sourceworks Series the first book solely dedicated to the subject of distillation, followed in 1512 by a much expanded version. In 1651, John French published The Art of Distillation the first major English compendium of practice, though it has been claimed''Industrial Engineering Chemistry'' (1936) page 677 that much of it derives from Braunschweig's work. This includes diagrams with people in them showing the industrial rather than bench scale of the operation. As alchemy evolved into the science of chemistry, vessels called retorts became used for distillations. Both alembics and retorts are forms of glassware with long necks pointing to the side at a downward angle which acted as air-cooled condensers to condense the distillate and let it drip downward for collection. Later, copper alembics were invented. Riveted joints were often kept tight by using various mixtures, for instance a dough made of rye flour.Sealing Technique, accessed 16 November 2006. These alembics often featured a cooling system around the beak, using cold water for instance, which made the condensation of alcohol more efficient. These were called pot stills. Today, the retorts and pot stills have been largely supplanted by more efficient distillation methods in most industrial processes. However, the pot still is still widely used for the elaboration of some fine alcohols such as cognac, Scotch whisky, tequila and some vodkas. Pot stills made of various materials (wood, clay, stainless steel) are also used by bootleggers in various countries. Small pot stills are also sold for the domestic productionTraditional Alembic Pot Still, accessed 16 November 2006. of flower water or essential oils. Early forms of distillation were batch processes using one vaporization and one condensation. Purity was improved by further distillation of the condensate. Greater volumes were processed by simply repeating the distillation. Chemists were reported to carry out as many as 500 to 600 distillations in order to obtain a pure compoundD. F. Othmer (1982) Distillation - Some Steps in its Development, in W. F. Furter (ed) A Century of Chemical Engineering ISBN 0-306-40895-3. In the early 19th century the basics of modern techniques including pre-heating and reflux were developed, particularly by the French, then in 1830 a British Patent was issued to Aeneas Coffey for a whiskey distillation columnA. Coffey British Patent 5974, 5 August 1830, which worked continuously and may be regarded as the archetype of modern petrochemical units. In 1877, Ernest Solvay was granted a U.S. Patent for a tray column for ammonia distillationUS Patent 198699 Improvement in the Ammonia-Soda Manufacture and the same and subsequent years saw developments of this theme for oil and spirits. With the emergence of chemical engineering as a discipline at the end of the 19th century, scientific rather than empirical methods could be applied. The developing petroleum industry in the early 20th century provided the impetus for the development of accurate design methods such as the McCabe-Thiele method and the Fenske equation. The availability of powerful computers has also allowed direct computer simulation of distillation columns. References Further reading * *Needham, Joseph (1980). [http://books.google.com/books?id=JvLroG7r2MYC&printsec=frontcover Science and Civilisation in China] Cambridge University Press: ISBN 052108573X *Allchin, F. R. (Mar., 1979). India: The Ancient Home of Distillation?. Man, New Series, Vol. 14, No. 1, pp. 55–63. Royal Anthropological Institute of Great Britain and Ireland. External links *Alcohol distillation *Case Study: Petroleum Distillation * Category:History of alcohol Category:History of chemistry